TW202338043A - Double-sided adhesive sheet, laminate, and method for manufacturing laminate - Google Patents

Abstract

The present invention provides a double-sided adhesive sheet by which in a situation where constituent optical members of a display device having a touch panel are equipped with metallic electrically conductive parts, ion migration at the metallic electrically conductive parts can be suppressed when the optical members are pasted together, and changes in resistance value due to a hygrothermal environment and ultraviolet rays can be suppressed. Provided are: a double-sided adhesive sheet for pasting together a first adherend and a second adherend, both of which are constituent optical members of a display device having a touch panel, wherein the first adherend and/or the second adherend has metallic electrically conductive parts, and the adhesive sheet has a sulfur content of 50 mg/kg or less, a spectral transmittance of 30% or less at a wavelength of 380 nm, and a water vapor transmission rate of 400 g/m2/24 h or less or a water absorption rate of 1.0% or less; a laminate; and a method for manufacturing the laminate.

Description

Double-sided adhesive sheet, laminated body, and method of manufacturing the laminated body

The present invention relates to a double-sided adhesive sheet, a laminated body and a method for manufacturing the laminated body.

In various fields, display devices such as liquid crystal displays (LCDs) or input devices such as touch panels are widely used. As touch panel methods, there are resistance film type, electrostatic capacitance type, etc., but the electrostatic capacitance type is mainly used. In the manufacture of display devices equipped with touch panels, transparent adhesive sheets are used for bonding optical components, and transparent adhesive sheets are also used for bonding display devices and input devices.

In small display devices equipped with touch panels such as smartphones, indium tin oxide (Indium tin oxide) is often used in the mesh electrode sensor (transparent conductive film) located on the screen from the viewpoint of transparency. Tin Oxide, ITO) and other metal oxides. In recent years, in the case of display devices equipped with touch panels with large screens of 10 inches or more, such as notebook personal computers (PCs), if ITO is used, the conductivity is insufficient and the sensitivity may be reduced. To cause malfunction, an electrode sensor section including a conductive section of metal such as silver or copper is used.

When an optical member constituting a display device equipped with a touch panel includes a metal conductive portion, problems may arise if a conventional transparent adhesive sheet is used. For example, when a mesh electrode sensor with a wiring width of several μm is used as a metal conductive portion, the following problem may occur: corrosion alone may cause the resistance value to increase and the sensor sensitivity to decrease. In addition, metal is sometimes used for the lead wiring in the frame portion of the screen. However, when the distance between lead wirings is set to about 10 μm as the frame of the touch panel becomes narrower, the following problem may occur: metal is generated. ion migration. If ion migration occurs, the electrode at the positive electrode will dissolve and break, or at the negative electrode, dendrites will form due to the precipitation of positive electrode components, resulting in a short circuit. In particular, ion migration is overwhelmingly likely to occur on the positive electrode side, while ion migration is less likely to occur on the negative electrode side. When evaluating ion migration, it is more preferable to use parallel wiring for evaluation than series wiring, and it is particularly preferable to evaluate the anode side.

In contrast, adhesive sheets that effectively prevent/suppress ion migration are known. For example, Patent Document 1 describes an adhesive composition that forms an adhesive for bonding a first display structural member and a second display structural member that have a step at least on the surface of the bonding side. In addition, in the adhesive composition, the first display structural member and/or the second display structural member has an electrode on at least the surface of the bonding side, and the adhesive composition contains (meth)acrylate polymer (A) , silane coupling agent with mercapto group (B) and active energy ray curing component (C).

On the other hand, regarding a method for preventing corrosion of ITO which is a metal oxide, Patent Document 2 describes an adhesive composition for laminating a conductive film and containing an acrylic polymer (A) and a cross-linking agent. (B), the acrylic polymer (A) contains 50% by weight or more of alkyl (meth)acrylate (a-1) and 0.5% by weight to 10% by weight of the monomer (a) having a hydroxyl group -2) An acrylic system obtained by copolymerizing a monomer with 0.1% to 5% by weight of a nitrogen-containing monomer (a-3) and having substantially no acidic group and a weight average molecular weight of 50,000 or more and less than 400,000 Polymer, among the alkyl (meth)acrylate (a-1), a homopolymer with a weight average molecular weight of 500,000 measured by the cup method at 40° C., 90% The water vapor transmission rate under RH is 500 g/m ² ‧day or less.

In addition, Patent Document 3 describes a conductive sheet that has: a support; and a conductive portion that is disposed on the support and includes conductive thin wires containing metallic silver and gelatin, and in the conductive sheet, the support is There is substantially no gelatin between the conductive thin wires, and the volume ratio (A/B) of the volume A of the metallic silver in the conductive thin wire to the volume B of the gelatin is 0.3 to 10.0. Furthermore, Patent Document 3 also describes a touch panel, which includes: a conductive sheet with the above-mentioned structure; and a transparent adhesive layer disposed on the conductive portion side of the conductive sheet, and in the touch panel, the transparent adhesive layer The acid value of the adhesive contained in the layer is less than 100 mgKOH/g, and the water absorption rate of the adhesive is less than 1.0%. [Prior art documents] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2017-014379 [Patent Document 2] Japanese Patent Application Publication No. 2013-047296 [Patent Document 3] Japanese Patent Application Publication No. 2014-209332

[Problem to be solved by the invention] Patent Document 1 describes that ion migration can be suppressed by using a silane coupling agent having a mercapto group. However, the present inventors conducted research and found that this may sometimes vary depending on the type of (meth)acrylate polymer, the blending ratio, etc. The composition of the adhesive composition causes insufficient suppression of ion migration. Furthermore, as a new problem when using a chain transfer agent or a silane coupling agent having a thiol group (thiol group) and when the adhesive sheet contains a sulfur component, the present inventors found that an increase in resistance value occurs due to corrosion of the metal conductive portion. In particular, it was found that changes in resistance value caused by hot and humid environments or ultraviolet rays significantly occur. In Patent Document 2, regarding the method of preventing corrosion of ITO, only attention is paid to preventing corrosion caused by acid by using an adhesive that does not contain substantially an acid component, and only focusing on water vapor transmission rate and moisture-heat resistance stability. relation. Patent Document 3 does not conduct research on suppressing the change in resistance value due to corrosion, and in particular does not suggest at all the change in resistance value due to corrosion of the metal conductive portion caused by a hot and humid environment and ultraviolet rays. In addition, Patent Document 3 describes the use of a migration inhibitor such as an organic mercapto compound to stabilize the metallic silver in the conductive part, but does not suggest suppressing the sulfur content.

The problem to be solved by the present invention is to provide a double-sided adhesive sheet that can suppress metal conduction when the optical members constituting a display device equipped with a touch panel include a metal conductive portion. Internal ion migration can be suppressed, and resistance changes caused by hot and humid environments and ultraviolet rays can be suppressed. [Means to solve the problem]

The specific structure and preferred structure of the present invention are as follows.

[1] A double-sided adhesive sheet for bonding a first adherend and a second adherend, both of which are optical members constituting a display device equipped with a touch panel, and in the double-sided adhesive sheet, the second adherend is At least one of the first adherend and the second adherend has a metal conductive part, the sulfur content is 50 mg/kg or less, the spectral transmittance at a wavelength of 380 nm is 30% or less, and the water vapor transmittance is 400 g/ m ² /24h or less, or the water absorption rate is less than 1.0%. [2] The double-sided adhesive sheet according to [1], wherein the first adherend is a touch panel, and the second adherend is an image display device or a cover material. [3] The double-sided adhesive sheet as described in [1] or [2], wherein the total light transmittance is 90% to 100%, the haze value is less than 1%, and it is approved by the International Commission on Illumination (International Commission on Illumination, The chromaticity b* specified in the CIE) 1976 L*a*b* color system is -1 to 1. [4] The double-sided adhesive sheet according to any one of [1] to [3], wherein the double-sided adhesive sheet has an adhesive layer, and the adhesive layer has a gel fraction of 40% to 90%. [5] The double-sided adhesive sheet according to any one of [1] to [4], wherein the double-sided adhesive sheet has an adhesive layer, and the adhesive layer contains the following base polymer, that is, it contains a polymer having a carbon number. A base polymer containing 70 to 98 mass % of 8 to 18 branched (meth)acrylate units and 1 to 20 mass % of units derived from hydroxyl-containing (meth)acrylate. [6] A laminated body including: the double-sided adhesive sheet according to any one of [1] to [5]; and a first adherend and a second adherend arranged on both sides of the double-sided adhesive sheet. Both surfaces are optical members constituting a display device equipped with a touch panel, and in the laminate, at least one of the first adherend and the second adherend has a metal conductive portion. [7] The laminated body according to [6], wherein the first adherend is a touch panel, the second adherend is an image display device or a cover material, and the touch panel and the image display device or the cover material At least one of them includes a transparent conductive film having a mesh conductive portion and a lead-out wiring connected to the mesh conductive portion. [8] The laminated body according to [6] or [7], wherein the conductive portion contains silver or copper. [9] A method of manufacturing a laminated body, including the following steps: using the double-sided adhesive sheet according to any one of [1] to [5] and an optical member constituting a display device equipped with a touch panel The pressurizing step is performed with one surface of each of the first and second adherends in contact with each other, and at least one of the first and second adherends has a metal conductive portion. [Effects of the invention]

According to the present invention, it is possible to provide a double-sided adhesive sheet that can suppress ions in the metal conductive portion when the optical members constituting a display device equipped with a touch panel include a metal conductive portion. Migration, and can suppress changes in resistance value caused by hot and humid environments and ultraviolet rays.

Hereinafter, the present invention will be described in detail. Description of the structural elements described below may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments.

[Double-sided adhesive sheet] The double-sided adhesive sheet of this embodiment is used to bond a first adherend and a second adherend, both of which are optical members constituting a display device equipped with a touch panel, and the double-sided adhesive sheet In the adhesive sheet, at least one of the first adherend and the second adherend has a metal conductive part, the sulfur content is 50 mg/kg or less, the spectral transmittance at a wavelength of 380 nm is 30% or less, and water vapor is transmitted The rate is less than 400 g/m ² /24h, or the water absorption rate is less than 1.0%. The double-sided adhesive sheet of this embodiment has the above-described structure. When the optical member constituting a display device equipped with a touch panel includes a metal conductive portion, when the optical members are bonded to each other, it is possible to suppress the formation of the metal conductive portion. Ion migration, and can suppress changes in resistance value caused by hot and humid environments and ultraviolet rays.

In this embodiment, by setting the sulfur content of the adhesive sheet below a specific range, the spectral transmittance at a wavelength of 380 nm is also set below a specific range, and the water vapor transmittance or water absorption rate is set below a specific range. , can suppress ion migration in metal conductive parts, and can suppress changes in resistance value caused by hot and humid environments and ultraviolet rays. Previously, in the technical field of adhesive sheets, it has been known to use a silane coupling agent having a mercapto group (a sulfur-containing group) to suppress ion migration (Japanese Patent Laid-Open No. 2017-014378, Japanese Patent Application Publication No. 2017-014378, in addition to Patent Document 1). Japanese Patent Publication No. 2020-114914, Japanese Patent Publication No. 6170202, etc.) or a method of using a sulfur-containing organic salt (Japanese Patent Publication No. 2021-504750) to form a cross-linked structure and inhibit corrosion. On the other hand, the present embodiment which sets the sulfur content to a specific range or less solves the above-mentioned problem based on a completely different knowledge from the conventional ones in the technical field of adhesive sheets.

Hereinafter, preferred forms of the double-sided adhesive sheet of this embodiment will be described.

<Characteristics of the double-sided adhesive sheet> (Water vapor transmission rate) In the first embodiment of the present invention, the water vapor transmission rate of the double-sided adhesive sheet is 400 g/m ² /24h or less. The water vapor transmittance of the double-sided adhesive sheet is preferably 300 g/m ² /24h or less, more preferably 200 g/m ² /24h or less. From the viewpoint of easily suppressing migration when the double-sided adhesive sheet is used for an optical member including a metal conductive portion, the water vapor transmittance is preferably within the above range. It is preferable that the water vapor transmittance of only the adhesive layer described below is within the above range.

(water absorption rate) In the second embodiment of the present invention, the water absorption rate of the double-sided adhesive sheet is 1.0% or less. The water absorption rate of the double-sided adhesive sheet is preferably 0.7% or less, more preferably 0.6% or less. From the viewpoint of easily suppressing migration when the double-sided adhesive sheet is used for an optical member including a metal conductive portion, the water absorption rate is preferably within the above range. It is preferable that the water absorption rate of only the adhesive layer described below is within the above range.

(Sulfur content) The sulfur content of the double-sided adhesive sheet of this embodiment is 50 mg/kg or less. The sulfur content of the double-sided adhesive sheet is preferably 40 mg/kg or less, more preferably 30 mg/kg or less. The sulfur content of the double-sided adhesive tablet is preferably 0 mg/kg, that is, it is preferably below the detection limit. The sulfur content is preferably in the above range from the viewpoint of easily suppressing changes in resistance value caused by a hot and humid environment when the double-sided adhesive sheet is used for an optical member including a metal conductive portion. Previously, little attention was paid to the increase in the resistance value of conductive parts of metals such as silver. However, as a subject, the inventors found that when an optical member having a conductive part of metal such as copper or silver is bonded together using a double-sided adhesive sheet, it is easy to cause an increase in the resistance value. Changes in resistance value caused by hot and humid conditions. It is preferable that the sulfur content of only the adhesive layer described below is within the above range. There is no particular limitation on the method of setting the sulfur content of the double-sided adhesive sheet below the above range. For example, when using a chain transfer agent when synthesizing the base polymer, use a chain transfer agent other than a sulfur-based chain transfer agent, use an additive that does not contain sulfur, or reduce the content of an additive that contains sulfur. Specifically, when a chain transfer agent is used in the polymerization of the base polymer, a chain transfer agent that does not contain thiol such as 2,4-diphenyl-4-methyl-1-pentene is used. Alternatively, a silane coupling agent other than the thiol-based silane coupling agent may be used as an additive, or the content of the thiol-based silane coupling agent may be reduced.

(380 nm transmittance) The double-sided adhesive sheet of this embodiment has a spectral transmittance of 30% or less at a wavelength of 380 nm. The spectral transmittance of the double-sided adhesive sheet at a wavelength of 380 nm is preferably less than 25%, and more preferably less than 20%. The spectral transmittance is preferably in the above range from the viewpoint of easily suppressing a change in resistance value caused by ultraviolet (UV) treatment when the double-sided adhesive sheet is used for an optical member including a metal conductive portion. Previously, no attention was paid to the change in resistance value due to UV light. However, as a subject, the inventors found that when an optical member having a conductive portion of metal such as copper or silver is bonded using a double-sided adhesive sheet, resistance is easily generated due to UV light. value changes. It is preferable that the spectral transmittance of only the adhesive layer described below is within the above range. The spectral transmittance of the double-sided adhesive sheet at a wavelength of 380 nm is preferably 0% or more, and from the perspective of the chromaticity b* value, it is more preferably 10% or more.

(Chroma b* value) In the double-sided adhesive sheet of this embodiment, the chromaticity b* value specified by the CIE1976L*a*b* color system in an environment of 23°C and 50% relative humidity is preferably -1 to 1, and more preferably More than -1 and less than 1, preferably more than -0.5 and less than 0.5. If the b* value is within the above range, the transparency required when using the double-sided adhesive sheet for an optical member or the color reproducibility of an image display device can be satisfied.

(total light transmittance) For double-sided adhesive sheets, the total light transmittance (a value measured in accordance with Japanese Industrial Standards (JIS) K 7361-1: 1997) in an environment of 23°C and 50% relative humidity can be set. is 80%. The total light transmittance of the double-sided adhesive sheet of this embodiment is preferably 90% to 100%. If the total light transmittance is within the above range, the transparency is high and it is suitable for optical applications.

(Haze value) In the double-sided adhesive sheet, the haze value can be set to 0% or more and 2% or less in an environment of 23°C and 50% relative humidity. The haze value of the double-sided adhesive sheet of this embodiment is more preferably 0% or more and less than 1%. If the haze value is within the above range, the transparency required when using the double-sided adhesive sheet for optical components can be satisfied, and the haze value is suitable for optical applications.

＜Structure of double-sided adhesive sheet＞ The double-sided adhesive sheet of this embodiment may include an adhesive layer and other layers, preferably only an adhesive layer. Examples of other layers include a support, a release sheet, and the like. FIG. 1 is a cross-sectional view showing an example of the structure of a double-sided adhesive sheet with a release sheet. The double-sided adhesive sheet 1 shown in FIG. 1 has release sheets (12a, 12b) on both surfaces of the adhesive layer 11. Furthermore, the double-sided adhesive sheet in Figure 1 is a carrier-less single-layer adhesive sheet and is a double-sided adhesive sheet.

＜Support＞ Examples of supports include: polystyrene, styrene-acrylic copolymer, acrylic resin, polyethylene terephthalate, polycarbonate, polyether ether ketone, triacetyl cellulose and other plastic films; Reflective films, electromagnetic wave shielding films and other optical films.

＜Peel-off sheet＞ The double-sided adhesive sheet of this embodiment preferably has an adhesive layer, and the surface of the adhesive layer is preferably covered with a release sheet. That is, this embodiment may be a double-sided adhesive sheet with a release sheet.

Examples of the release sheet include a release laminated sheet having a release sheet base material and a release agent layer provided on one side of the release sheet base material, or a polyethylene film or a polypropylene film as a low polarity base material, etc. Polyolefin film. Paper and polymer films can be used as the base material for the release sheet in the release laminated sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition-type or condensation-type silicone-based release agent or a long-chain alkyl group-containing compound can be used. In particular, an addition-type silicone release agent with high reactivity can be suitably used. Specific examples of the silicone-based release agent include BY24-4527, SD-7220, etc. manufactured by Toray Dow Corning Silicone Co., Ltd., or KS-3600 and KS manufactured by Shin-Etsu Chemical Industry Co., Ltd. -774, X62-2600, etc. In addition, it is preferable that the silicone-based stripping agent contains an organic silicon compound having a SiO ₂ unit and a (CH ₃ ) ₃ SiO _1/2 unit or a CH ₂ =CH(CH ₃ )SiO _1/2 unit, that is, a silicone resin. . Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404, etc. manufactured by Toray Dow Corning Silicone Co., Ltd., or KS-3800, manufactured by Shin-Etsu Chemical Industry Co., Ltd. X92-183 etc.

In order to facilitate peeling of the peeling sheet 12 shown in FIG. 1, it is preferable that the peeling properties of the peeling sheet 12a and the peeling sheet 12b are different. That is, if the releasability from one of them is different from the releasability from the other, it is easy to peel off only the release sheet 12 with high releasability first. In this case, the peelability of the peeling sheet 12a and the peeling sheet 12b as the peeling sheet 12 may be adjusted according to the lamination method or the lamination order.

＜Adhesive layer＞ The double-sided adhesive sheet of this embodiment preferably includes an adhesive layer. The thickness of the adhesive layer can be appropriately set according to the purpose and is not particularly limited. Generally, the thickness of the adhesive layer is preferably in the range of 10 μm or more and 500 μm or less, more preferably 20 μm or more and 450 μm or less, further preferably 30 μm or more and 450 μm or less, particularly preferably 40 μm or more and 40 μm or more. 400 μm or less, more preferably 40 μm or more and 350 μm or less, particularly preferably 40 μm or more and 300 μm or less. By setting the thickness of the adhesive layer within the above range, unevenness followability can be sufficiently ensured, and durability can be improved. In addition, by setting the thickness of the adhesive layer within the above range, the double-sided adhesive sheet can be easily produced.

(gel fraction) The gel fraction of the adhesive layer is preferably 40 mass% or more, more preferably 60 mass% or more, and further preferably 65 mass% or more. In addition, the gel fraction of the adhesive layer is preferably 90 mass% or less. From the viewpoint of easily reducing the water vapor transmission rate or water absorption rate, it is preferable to set the gel fraction to be equal to or higher than the lower limit value. By setting the gel fraction below the upper limit, the adhesive force can be improved.

The composition of the adhesive layer is not particularly limited, but it preferably contains the base polymer (A). The adhesive layer preferably contains a cross-linking agent (B), a silane coupling agent (C), and an ultraviolet absorber (D) as optional additives, and preferably further contains a solvent (E).

(Base polymer (A)) The base polymer (A) is not particularly limited, but it preferably has a unit derived from (meth)acrylate. The base polymer (A) preferably has transparency to an extent that does not reduce the visibility of the display device. In addition, in this specification, a "unit" is a repeating unit (monomeric unit) which constitutes a polymer. The base polymer (A) preferably contains a unit (a1) derived from a non-crosslinkable (meth)acrylate and a unit (a2) derived from a (meth)acrylic acid monomer having a crosslinkable functional group. .

Preferably, at least one of the unit (a1) derived from a non-crosslinkable (meth)acrylate and the unit (a2) derived from a (meth)acrylic acid monomer having a crosslinkable functional group is the source. Units from methacrylate. For example, when the unit (a1) derived from a non-crosslinkable (meth)acrylate is a unit derived from a non-crosslinkable acrylate, the unit (a1) derived from a (meth)acrylic acid monomer having a crosslinkable functional group The monomer unit (a2) is preferably a unit derived from a methacrylic acid monomer having a crosslinkable functional group. Alternatively, when the unit (a2) derived from a (meth)acrylic acid monomer having a crosslinkable functional group is a unit derived from an acrylic acid monomer, it is derived from a non-crosslinkable (meth)acrylate. The unit (a1) is preferably 50% by mass or more of units derived from non-crosslinked methacrylate.

-Unit (a1) derived from non-crosslinked (meth)acrylate- The unit (a1) derived from a non-crosslinkable (meth)acrylate is preferably a unit derived from a (meth)acrylate having a branched chain having 8 to 18 carbon atoms. Examples of such (meth)acrylic acid alkyl esters include 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, and the like. These may be used individually by 1 type, and may use 2 or more types together. Among these, it is preferable to use 2-ethylhexyl (meth)acrylate as the non-crosslinked (meth)acrylate unit (a1). Here, when the unit (a2) derived from a (meth)acrylic acid monomer having a crosslinkable functional group is a unit derived from an acrylic acid monomer, the unit derived from a non-crosslinkable (meth)acrylic acid The unit (a1) of the ester is preferably a unit derived from a non-crosslinked methacrylate. In this case, the unit (a1) derived from a non-crosslinked (meth)acrylate is preferably a unit derived from a methacrylate having a branched chain having 8 to 18 carbon atoms, more preferably methacrylic acid. 2-Ethyl Hexyl Methacrylate (2EHMA).

The number of carbon atoms in the branched alkyl group of the unit (a1) derived from the non-crosslinked (meth)acrylate may be 8 to 18, and is preferably 8 or more and 10 or less. By setting the carbon number of the branched alkyl group within the above range, the degree of polymerization of the base polymer (A) can be easily controlled, and an adhesive composition excellent in processability can be obtained.

The content of the unit (a1) derived from the non-crosslinked (meth)acrylate in the base polymer (A) is preferably 70 mass % or more, more preferably 75 mass % or more, more preferably 80 mass % or more. In addition, the content of the unit (a1) is preferably 95 mass% or less, more preferably 90 mass% or less. From the viewpoint of controlling water vapor transmission rate or hygroscopicity, the content of unit (a1) is preferably not less than the lower limit of the above range, and from the viewpoint of controlling adhesive performance, the content of unit (a1) is preferably not less than the upper limit of the above range. below the limit.

-Unit (a2) derived from a (meth)acrylic acid monomer having a cross-linkable functional group- Examples of the unit (a2) derived from a (meth)acrylic acid monomer having a crosslinkable functional group include a hydroxyl (Hydroxy)-containing monomer unit, an amine group-containing monomer unit, and a glycidyl-containing monomer unit. monomer units containing carboxyl groups, monomer units containing carboxyl groups, etc. These single volume units may be one type, or two or more types. The hydroxyl-containing monomer unit is a repeating unit derived from the hydroxyl-containing monomer. Examples of the hydroxyl-containing monomer include hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. (meth)acrylic acid mono(diethylene glycol) and other (meth)acrylic acid [(mono, di or poly)alkylene glycol]; (meth)acrylic acid monocaprolactone and other (meth)acrylic acid Acrylic lactone. Here, when the unit (a1) derived from a non-crosslinkable (meth)acrylate is a unit derived from a non-crosslinkable acrylate, it is derived from (meth)acrylic acid having a crosslinkable functional group The unit (a2) of the monomer is preferably a unit derived from a methacrylic acid monomer having a crosslinkable functional group. In this case, the hydroxyl-containing monomer is preferably a hydroxyl-containing methacrylate, methacrylic acid [(mono, di or poly)alkylene glycol], methacrylic acid lactone, and more preferably a hydroxyl-containing monomer. Methacrylate, particularly preferably 2-Hydroxy Ethyl Methacrylate (2HEMA). Examples of the amine group-containing monomer unit include repeating units derived from amine group-containing monomer units such as (meth)acrylamide and allylamine. Examples of the glycidyl group-containing monomer unit include repeating units derived from glycidyl group-containing monomer units such as glycidyl (meth)acrylate. Examples of the carboxyl group-containing monomer unit include acrylic acid and methacrylic acid.

Relative to the total mass of the base polymer (A), the unit (a2) derived from a (meth)acrylic acid monomer having a crosslinkable functional group in the base polymer (A) (preferably a hydroxyl-containing ( The content of (meth)acrylate) is preferably 1.0 mass% or more, more preferably 5.0 mass% or more, and particularly preferably 10.0 mass% or more. In addition, the content of the unit (a2) is preferably 30 mass% or less, more preferably 20 mass% or less, and particularly preferably 15 mass% or less. From the viewpoint of suppressing an increase in resistance value in a hot and humid environment or controlling the gel fraction, the content of unit (a2) is preferably not less than the lower limit of the above range, and from the viewpoint of controlling water vapor permeability or hygroscopicity Specifically, it is preferably below the upper limit of the range. Among the units (a2) derived from a (meth)acrylic acid monomer having a cross-linkable functional group, from the viewpoint of suppressing an increase in the resistance value in a hot and humid environment or controlling the gel fraction, the hydroxyl-containing (meth)acrylic acid monomer is The content of the acrylic acid ester is preferably not less than the lower limit of the above range, and from the viewpoint of controlling water vapor transmission rate or hygroscopicity, preferably not more than the upper limit of the above range.

-Other single volume units- If necessary, the base polymer (A) may have a unit (a1) derived from a non-crosslinkable (meth)acrylate and a (meth)acrylic acid monomer unit (a2) having a crosslinkable functional group. other single volume units. Examples of other monomer units include (meth)acrylate units having 4 or less carbon atoms or 10 or more carbon atoms. Specific examples include: (methylmeth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate, n-decyl(meth)acrylate, Lauryl (meth)acrylate, stearyl (meth)acrylate, etc. In addition, as other (meth)acrylate units, a (meth)acrylate unit having a linear alkyl group having a carbon number of 5 or more and 9 or less may be included. Specific examples include: (n-pentylmeth)acrylate, n-hexyl(meth)acrylate, n-heptyl(meth)acrylate, n-octyl(meth)acrylate, and n-nonyl(meth)acrylate. wait. Furthermore, examples of other (meth)acrylate units include (meth)acrylate units having a cyclic group such as cyclohexylmeth)acrylate and benzyl (meth)acrylate, or (meth)acrylate units. Acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinylpyrrolidone, vinylpyridine, etc. The content of other monomer units in the base polymer (A) is preferably 20 mass% or less, more preferably 10 mass% or less, and particularly preferably 5 mass% or less.

-Physical properties of base polymer (A)- The weight average molecular weight of the base polymer (A) is preferably from 100,000 to 2 million, more preferably from 300,000 to 1.5 million. By setting the weight average molecular weight within the above range, the semi-hardened state of the adhesive sheet can be maintained and sufficient unevenness following properties can be ensured. In addition, the weight average molecular weight of the base polymer (A) is the value before crosslinking with a crosslinking agent. The weight average molecular weight is measured by gel permeation chromatography (GPC) and is a value determined based on a polystyrene standard. As the base polymer (A), a commercially available polymer may be used, or a polymer synthesized by a known method may be used.

-Content of base polymer (A)- The content of the base polymer (A) is preferably 75 mass% or more, more preferably 80 mass% or more, further preferably 85 mass% or more relative to the total mass of the adhesive composition. In addition, the content of the base polymer (A) is preferably 98 mass% or less, more preferably 95 mass% or less, and still more preferably 90 mass% or less.

(Crosslinking agent (B)) The cross-linking agent (B) reacts with the base polymer (A) by heat. The crosslinking agent (B) may be selected from, for example, an isocyanate compound, an epoxy compound, an oxazoline compound, an aziridine compound, and a metal chelate in consideration of the reactivity with the crosslinkable functional group of the base polymer (A). It is appropriately selected from known cross-linking agents such as compound compounds and butylated melamine compounds. For example, when a hydroxyl group is included as a crosslinkable functional group, an isocyanate compound can be used depending on the reactivity of the hydroxyl group. From the viewpoint that the unit (a2) derived from the (meth)acrylic acid monomer having a crosslinkable functional group can be easily crosslinked, it is preferable to use an isocyanate compound or an epoxy compound.

Examples of the isocyanate compound include toluene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and the like. Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, and neopentyl glycol diglycidyl ether. Glycidyl ether, 1,6-hexanediol diglycidyl ether, tetraglycidylxylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, trihydroxy Methylpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc.

As the cross-linking agent (B) such as an isocyanate compound, commercially available products can be used. Examples of commercially available products include Takenate D-110N (isocyanate compound, manufactured by Mitsui Chemicals Co., Ltd.) and the like.

As the cross-linking agent (B), one type may be used alone, or two or more types may be used in combination. The content of the cross-linking agent (B) in the adhesive composition can be appropriately selected depending on the desired adhesive properties, etc., and is not particularly limited. It can be 0.01 parts by mass or more based on 100 parts by mass of the base polymer (A). and 5 parts by mass or less, and may be 0.10 parts by mass or more and 3 parts by mass or less. In addition, the content of the cross-linking agent (B) may be 0.01 mass % or more and 5.0 mass % or less, and may be 0.02 mass % or more and 2.0 mass % or less relative to the total mass of the adhesive composition.

(Silane coupling agent (C)) As the silane coupling agent, for example, a silane coupling agent containing a reactive functional group can be used. Examples include mercapto-based silane coupling agents, (meth)acrylic-based silane coupling agents, isocyanate-based silane coupling agents, epoxy-based silane coupling agents, and amino-based silane coupling agents. Examples of the mercapto-based silane coupling agent include mercaptoalkoxysilane compounds (for example, mercapto-substituted alkoxy oligomers, etc.), but the content needs to be noted as described below. Examples of other reactive functional group-containing silane coupling agents include those described in paragraphs [0094] to [0096] of Japanese Patent Application Laid-Open No. 2020-114914, which is hereby incorporated by reference. Among these, from the viewpoint of reducing the sulfur content of the double-sided adhesive sheet, a (meth)acrylic silane coupling agent, an isocyanate silane coupling agent, an epoxy silane coupling agent, and an amino silane coupling agent are preferred. , more preferably epoxy silane coupling agent.

As the silane coupling agent, commercially available products can be used. Examples of commercially available products include an epoxy-based silane coupling agent (KBM403, manufactured by Shin-Etsu Chemical Industries, Ltd.), a mercapto-based silane coupling agent (X-41-1810, manufactured by Shin-Etsu Chemical Industries, Ltd.), and the like.

When the double-sided adhesive sheet contains a silane coupling agent, the content of the silane coupling agent is preferably 1 part by mass or less, and more preferably 0.5 part by mass relative to 100 parts by mass of the base polymer (A). the following. From the viewpoint of reducing the sulfur content of the double-sided adhesive sheet, the content of the mercapto-based silane coupling agent is preferably 0.06 parts by mass or less, more preferably 0.04 parts by mass, based on 100 parts by mass of the base polymer (A) portion or less.

(UV absorber (D)) The ultraviolet absorber can be selected from those with maximum absorption wavelength in the ultraviolet region. It is especially suitable for UV absorbers with maximum absorption wavelength above 350 nm. Examples of the ultraviolet absorber having a maximum absorption wavelength at a wavelength of 350 nm or more include a benzotriazole-based ultraviolet absorber or a benzotriazine-based ultraviolet absorber. Examples of ultraviolet absorbers include compounds represented by the following general formula (1) or general formula (2).

[Chemical 1] General formula (1)

In the above formula, R ¹ represents a hydrogen atom, a halogen atom, an alkoxy group with 1 to 4 carbon atoms, a nitro group or a cyano group, R ² represents a hydrogen atom or an alkyl group with 1 to 8 carbon atoms, and R ³ represents an alkyl group. System structure.

[Chemical formula 2] General formula (2)

In the above formula, R ⁴ , R ⁵ and R ⁶ are hydrogen atoms, hydroxyl groups, alkyl structures or halogen atoms, and not all of R ⁴ , R ⁵ and R ⁶ are hydrogen atoms. In addition, the alkyl-based structure is a concept including a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, and other substituents mainly composed of an alkyl group.

The ultraviolet absorber preferably contains at least one compound that is oily or liquid at 23°C. Among them, ultraviolet absorbers that are particularly preferably used are those that have improved compatibility by introducing an alkyl group with a large molecular weight into the aromatic ring of the basic skeleton and exhibit an oily or liquid state at 23°C. UV absorber. Here, showing an oily or liquid state at 23° C. means that only the ultraviolet absorber has fluidity even without a diluting solvent.

As the ultraviolet absorber, commercially available products can be used. Examples of commercially available products include triazine-based ultraviolet absorbers (Tinuvin 477) manufactured by BASF Co., Ltd. and benzotriazole-based ultraviolet absorbers (Tinuvin). ) 384-2, Tinuvin PS), etc.

The content of the ultraviolet absorber is preferably 0.1 to 8.0 parts by mass, more preferably 0.5 to 4.0 parts by mass, and particularly preferably 1.0 to 3.0 parts by mass relative to 100 parts by mass of the base polymer (A). One type of the ultraviolet absorber may be used alone, or two or more types may be used in combination. When two or more types of ultraviolet absorbers are used in combination, it is preferable that the total mass is within the above range.

(Solvent (E)) The adhesive composition may further contain a solvent (E). The solvent (E) is used to improve the coating adaptability of the adhesive composition. Examples of such solvent (E) include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; methylene chloride and trichloroethane. Halogenated hydrocarbons such as alkane, trichlorethylene, tetrachloroethylene, dichloropropane; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, diacetone alcohol; diethyl ether, diisopropyl ether , dioxane, tetrahydrofuran and other ethers; acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone and other ketones; methyl acetate, ethyl acetate, butyl acetate, acetic acid Isobutyl acetate, amyl acetate, ethyl butyrate and other esters; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono Polyols such as methyl ether acetate and their derivatives.

One type of solvent (E) may be used alone, or two or more types may be used in combination. In the adhesive composition, the content of the solvent (E) is not particularly limited, but may be 25 parts by mass or more and 500 parts by mass or less based on 100 parts by mass of the base polymer (A), and may be 30 parts by mass or more. And less than 400 parts by mass. In addition, the content of the solvent (E) may be 10 mass % or more and 90 mass % or less, and may be 20 mass % or more and 80 mass % or less relative to the total mass of the adhesive composition.

(other ingredients) The adhesive composition may also contain components other than those mentioned above within a range that does not impair the effects of the present invention. As other components, if necessary, components known as additives for adhesives may be selected, such as plasticizers, monomers, polymerization initiators, antioxidants, metal corrosion inhibitors, adhesion-imparting agents, hindered amine compounds, etc. Choose from light stabilizers, etc. As plasticizers, nonfunctional acrylic polymers can be used. Examples of antioxidants include phenolic antioxidants, amine antioxidants, lactone antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. These antioxidants may be used individually by 1 type, or in combination of 2 or more types. Examples of metal corrosion inhibitors include benzotriazole-based resins. Examples of the tackifier include rosin-based resin, terpene-based resin, terpene-phenol-based resin, coumarone-indene-based resin, styrene-based resin, xylene-based resin, and phenol-based resin. , petroleum resin, methacrylic resin, etc.

＜Manufacturing method of double-sided adhesive sheet＞ The manufacturing method of the double-sided adhesive sheet of this embodiment is not particularly limited. The manufacturing step of the double-sided adhesive sheet of this embodiment preferably includes the step of applying an adhesive composition on the release sheet to form a coating film.

Hereinafter, the process of applying an adhesive composition to a release sheet to form a coating film will be described typically. By heating the coating film, the base polymer (A) and the cross-linking agent (B) react to form a semi-hardened product (adhesive sheet). In order to bring the adhesive composition into a semi-hardened state, the following aging treatment can be performed, that is, after application, the solvent is removed, and then the adhesive sheet is allowed to stand at a certain temperature for a certain period of time. The aging treatment can be performed by leaving it still at 23° C. for 7 days, for example.

The adhesive composition forming the adhesive sheet can be applied using a known coating device. Examples of the coating device include: blade coater, air knife coater, roller coater, rod coater, gravure coater, micro gravure coater, rod blade coater, lip coater cloth machine, die coating machine, curtain coating machine, etc. In addition, the coating film can be heated using a known heating device such as a heating furnace or an infrared lamp.

(How to use adhesive sheet) In the method of using the double-sided adhesive sheet of this embodiment, the peeling sheet on the light peeling side of the adhesive sheet is peeled off, and the adhesive layer is bonded to the surface of the first adherend, and then the heavy layer is bonded. The peeling sheet on the peeling side is peeled off, and the adhesive layer on the side opposite to the first adherend is brought into contact with the second adherend. When the adhesive sheet is a semi-hardened adhesive sheet with post-hardening properties, active energy rays can be irradiated in this state to completely harden the adhesive layer.

[Laminated body] The laminated body of this embodiment includes: the double-sided adhesive sheet; and a first adherend and a second adherend, which are arranged on both surfaces of the double-sided adhesive sheet and constitute a display device equipped with a touch panel. An optical member, wherein in the laminated body, at least one of the first adherend and the second adherend has a metal conductive portion.

The first adherend and the second adherend are preferably optical members constituting an image display device having a liquid crystal module equipped with a touch panel with a cover. The laminate of the present embodiment The body preferably has an optical member constituting an image display device having a liquid crystal module equipped with a touch panel with a cover. The cover material is a member provided on the side of the touch panel opposite to the image display device. Examples of the cover material include cover glass or a resin cover lens.

The laminated body of this embodiment is preferably obtained by bringing the adhesive layer of the double-sided adhesive sheet into contact with the surface of the adherend, and in this state, using an autoclave or the like to pressurize, heat, Degassing is a step to improve adhesion. In the laminated body of this embodiment, after the adhesive layer of the double-sided adhesive sheet is brought into contact with the surface of the adherend, the adhesive layer may not be completely cured.

FIG. 2 is a cross-sectional view showing an example of the structure of the laminated body 20 in which the double-sided adhesive sheet 21 of this embodiment is bonded to the first adherend 22 and the second adherend 24 . As shown in FIG. 2 , the first adherend 22 and the second adherend 24 may have conductive portions (27a, 27b, 27c, 27d) serving as step portions. In FIG. 2 , the first adherend 22 has conductive parts (27a, 27b), and the second adherend 24 has conductive parts (27c, 27d). In addition, the thickness of the conductive parts (27a, 27b, 27c, 27d) is usually 5 μm or more and 60 μm or less. As mentioned above, the double-sided adhesive sheet 21 of this embodiment can also be bonded to a member having a stepped portion, and preferably can follow the unevenness generated by the stepped portion.

In this embodiment, the first adherend and the second adherend are disposed on both surfaces of the double-sided adhesive sheet, and both are optical members constituting a display device equipped with a touch panel. In addition, at least one of the first adherend and the second adherend has a metal conductive portion. Examples of optical members include structural members in optical products such as touch panels and image display devices. Examples of structural members of the touch panel include: a metal film in which a mesh metal film or metal wires are provided on a transparent resin film; and metallic glass in which a mesh metal film or metal wires are provided on the surface of a glass plate. , ITO film in which an ITO film is provided on a transparent resin film, ITO glass in which an ITO film is provided on the surface of a glass plate, transparent conductive films and hard-coat films obtained by coating conductive polymers on these transparent resin films , fingerprint-resistant film, etc. Examples of structural members of image display devices include antireflection films, alignment films, polarizing films, retardation films, and brightness improvement films used in liquid crystal display devices. Examples of materials used for these components include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cyclic olefin polymers, and triethylene. Enzyme cellulose, polyimide, ethanolized cellulose, etc.

When the double-sided adhesive sheet of this embodiment is a double-sided adhesive sheet, it can be used for bonding two adherends. In this case, the double-sided adhesive sheet of this embodiment can be used for laminating metal films to each other, laminating metal films and metallic glass, laminating metal films and ITO films, and laminating ITO films and metals inside the touch panel. The bonding of glass, the bonding of the metal film of the touch panel and the liquid crystal panel, the bonding of the cover material and the metal film, etc. The double-sided adhesive sheet of this embodiment is particularly preferably used for bonding the cover material and the metal film, and more preferably, is used for bonding the cover material and the metal film of the touch panel.

In this embodiment, the first adherend is preferably a touch panel, and the second adherend is preferably an image display device or a cover material (preferably a cover glass). In addition, it is more preferable that at least one of the touch panel, the image display device, or the cover material includes a transparent conductive film having a mesh conductive portion and lead wiring connected to the mesh conductive portion. Particularly preferably, the cover material includes a transparent conductive film having a mesh conductive portion and lead wiring connected to the mesh conductive portion.

In this embodiment, the metal conductive part is preferably an alloy containing copper, silver, iron, tin, zinc, nickel, molybdenum, chromium, tungsten, lead and two or more metals selected from these, and more preferably It may contain copper, copper alloy, silver, or silver alloy, and particularly preferably it may contain silver or silver alloy. The conductive part containing silver is preferably made of a material containing silver halide. The double-sided adhesive sheet of this embodiment is most suitable for applications including conductive thin wires exposed from a photosensitive material containing silver halide as described in [0006] to [0160] of Japanese Patent Laid-Open No. 2014-209332, A body to be adhered containing conductive thin wires produced by development. Preferred examples of silver alloys include alloys obtained by adding palladium and copper to silver. Unoxidized metals have a higher tendency to ionize than metal oxides such as ITO. According to the double-sided adhesive sheet of this embodiment, ion migration can be suppressed even in this case. As a result, when the double-sided adhesive sheet of this embodiment comes into contact with electrodes or wiring that have been refined and have a narrow pitch, it can prevent the electrode or wiring from being disconnected or short-circuited.

[Method for manufacturing laminated body] The manufacturing method of the laminated body of this embodiment includes the following steps: combining the double-sided adhesive sheet of this embodiment with a first adherend and a second adherend, both of which are optical members constituting a display device equipped with a touch panel. In a state where one of the respective surfaces is in contact, at least one of heating and pressurizing steps is performed, and at least one of the first adherend and the second adherend has a metal conductive portion. There is no particular limitation on the step of pressurizing the double-sided adhesive sheet of this embodiment in a state of contacting one surface of each of the first adherend and the second adherend. It is preferable to perform degassing by a pressurizing step, or to perform a degassing step before or after the pressurizing step. In addition, it is preferable to perform the pressurizing step simultaneously with heating, or to further perform the heating step before or after the pressurizing step. For example, it is preferable to include the following steps: bringing the double-sided adhesive sheet into contact with the surface of the first adherend and/or the second adherend, and performing pressurization, heating, and dehydration using an autoclave or the like in this state. Bubble or perform pressurization and vacuum degassing in this state to improve the adhesion. [Example]

Hereinafter, the characteristics of the present invention will be described more specifically with reference to Examples and Comparative Examples. The materials, usage amounts, proportions, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited to the specific examples shown below.

[Synthesis example] <Synthesis of cross-linked (meth)acrylic copolymer A-1> For the monomer prepared by blending 2-ethylhexyl methacrylate (2EHMA) and 2-Hydroxy Ethyl Acrylate (2HEA) in a mass ratio of 85:15, as a polymer In ethyl acetate as a solvent, in the presence of azobisisobutyronitrile (AIBN), it was heated to 60°C and polymerized. Thereby, a solution (a-1) of the crosslinkable (meth)acrylic acid copolymer (A-1) having a solid content concentration of 50% by mass and a weight average molecular weight of 450,000 was obtained.

<Synthesis of cross-linked (meth)acrylic copolymer A-2> For a monomer prepared by blending 2-ethylhexyl acrylate (2EHA) and 2-hydroxyethyl methacrylate (2HEMA) at a mass ratio of 85:15, in ethyl acetate as a polymerization solvent , heated to 60°C in the presence of azobisisobutyronitrile (AIBN) and polymerized. Thereby, a solution (a-2) of the crosslinkable (meth)acrylic acid copolymer (A-2) with a solid content concentration of 50% by mass and a weight average molecular weight of 480,000 was obtained.

<Synthesis of cross-linked (meth)acrylic copolymer A-3> For a monomer prepared by blending 2-ethylhexyl methacrylate (2EHMA) and 2-hydroxyethyl acrylate (2HEA) at a mass ratio of 95:5, in ethyl acetate as a polymerization solvent , heated to 60°C in the presence of azobisisobutyronitrile (AIBN) and polymerized. Thereby, a solution (a-3) of the crosslinkable (meth)acrylic acid copolymer (A-3) having a solid content concentration of 50% by mass and a weight average molecular weight of 440,000 was obtained.

<Synthesis of cross-linked (meth)acrylic copolymer A-4> For a monomer prepared by blending 2-ethylhexyl acrylate (2EHA) and 2-hydroxyethyl methacrylate (2HEMA) at a mass ratio of 95:5, in ethyl acetate as a polymerization solvent , heated to 60°C in the presence of azobisisobutyronitrile (AIBN) and polymerized. Thereby, a solution (a-4) of the crosslinkable (meth)acrylic acid copolymer (A-4) having a solid content concentration of 50% by mass and a weight average molecular weight of 460,000 was obtained.

<Synthesis of cross-linked (meth)acrylic copolymer A-5> For a monomer prepared by blending 2-ethylhexyl methacrylate (2EHMA) and 2-hydroxyethyl acrylate (2HEA) at a mass ratio of 70:30, in ethyl acetate as a polymerization solvent , heated to 60°C in the presence of azobisisobutyronitrile (AIBN) and polymerized. Thereby, a solution (a-5) of the crosslinkable (meth)acrylic acid copolymer (A-5) having a solid content concentration of 50% by mass and a weight average molecular weight of 450,000 was obtained.

<Synthesis of cross-linked (meth)acrylic copolymer A-6> A monomer prepared by mixing butyl acrylate (BA) and 2-hydroxyethyl acrylate (2HEA) at a mass ratio of 85:15 was added to ethyl acetate as a polymerization solvent. Heated to 60°C in the presence of azobisisobutyronitrile (AIBN) and polymerized. Thereby, a solution (a-6) of the crosslinkable (meth)acrylic acid copolymer (A-6) with a solid content concentration of 50 mass % and a weight average molecular weight of 500,000 was obtained.

＜Weight average molecular weight＞ The weight average molecular weight of the cross-linked (meth)acrylic acid copolymer (A) and the methyl methacrylate polymer (B) was measured using a gel permeation chromatograph (GPC) using the following method . The measurement conditions of GPC are as follows. ‧Solvent: Tetrahydrofuran ‧Pipe string: Shodex KF801, KF803L, KF800L, KF800D (use four strings manufactured by Showa Denko Co., Ltd.) ‧Column temperature: 40℃ ‧Sample concentration: 0.5 mass% ‧Detector: RI-2031plus (manufactured by JASCO) ‧Pump: RI-2080plus (manufactured by JASCO) ‧Flow rate (flow rate): 0.8 ml/min ‧Injection volume: 10 μl ‧Calibration curve: Calibration curve obtained using 10 samples based on standard polystyrene Shodex standard polystyrene (manufactured by Showa Denko Co., Ltd.) with Mw=1320 to 2,500,000.

[Example 1] <Adjustment of adhesive composition> The solution (a-1) of the acrylic copolymer (A-1) contains 0.1 parts by mass of an isocyanate compound (D-110N, manufactured by Mitsui Chemicals Co., Ltd.) as a cross-linking agent, 0.02 parts by mass of The raw materials of the epoxy-based silane coupling agent (KBM403, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) and 1.2 parts by mass of the ultraviolet absorber (Tinuvin 384-2, manufactured by BASF) were used at a concentration of 45 Add mass % to ethyl acetate and stir to prepare an adhesive composition.

＜Preparation of double-sided adhesive sheet＞ The adhesive composition prepared as described above is evenly applied using an applicator so that the coating thickness after drying becomes 50 μm. The thickness of the release agent layer treated with the silicone-based release agent is 50 μm. A coating film is formed on the surface of a polyethylene terephthalate film (First Release Sheet, manufactured by Oji Airfit (F-Tex) Co., Ltd., 50RL-07 (2)). The coating film was dried at 80° C. for 3 minutes using an air circulation constant-temperature oven, thereby forming an adhesive layer (double-sided adhesive sheet of Example 1) on the surface of the first release sheet.

＜Preparation of adhesive sheet with release sheet＞ Then, a second release sheet (38RL-07 (L) manufactured by Oji Airft (F-Tex) Co., Ltd., manufactured by F-Tex)) with a thickness different from that of the first release sheet was bonded to the surface of the adhesive layer. Cured for 14 days at 23°C and relative humidity of 50%. Thereby, an adhesive sheet with a release sheet having a structure of first release sheet/adhesive layer/second release sheet in which an adhesive layer (adhesive sheet) is sandwiched between a pair of release sheets having a difference in release force is obtained.

[Example 2] A tape was obtained by the same procedure as in Example 1, except that the solution (a-1) of the acrylic copolymer (A-1) was changed to the solution (a-2) of the acrylic copolymer (A-2). Adhesive sheet for peel-off sheet.

[Example 3] The solution (a-1) of the acrylic copolymer (A-1) was changed into the solution (a-2) of the acrylic copolymer (A-2), and an epoxy silane coupling agent (KBM403, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) was obtained. An adhesive sheet with a release sheet was obtained by the same procedure as in Example 1, except that the coupling agent was changed to a mercapto-based silane coupling agent (X-41-1810, manufactured by Shin-Etsu Chemical Industry Co., Ltd.).

[Example 4] A tape was obtained by the same procedure as in Example 3, except that the solution (a-3) of the acrylic copolymer (A-3) was changed into the solution (a-4) of the acrylic copolymer (A-4). Adhesive sheet for peel-off sheet.

[Example 5] A tape was obtained by the same procedure as in Example 1, except that the solution (a-1) of the acrylic copolymer (A-1) was changed to the solution (a-5) of the acrylic copolymer (A-5). Adhesive sheet for peel-off sheet.

[Example 6] A tape release sheet was obtained by the same procedure as Example 1, except that the added amount of the isocyanate compound (D-110N, manufactured by Mitsui Chemicals Co., Ltd.) as a cross-linking agent was changed from 0.1 parts by mass to 0.04 parts by mass. adhesive piece.

[Comparative example 1] A tape release sheet was obtained by the same procedure as Example 3, except that the added amount of the mercapto silane coupling agent (X-41-1810, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) was changed from 0.02 parts by mass to 0.04 parts by mass. adhesive piece.

[Comparative example 2] An adhesive sheet with a release sheet was obtained by the same procedure as in Example 1, except that 1.2 parts by mass of an ultraviolet absorber (Tinuvin 384-2, manufactured by BASF) was not added.

[Comparative example 3] A tape was obtained by the same procedure as in Example 1, except that the solution (a-1) of the acrylic copolymer (A-1) was changed to the solution (a-6) of the acrylic copolymer (A-6). Adhesive sheet for peel-off sheet.

[Characteristics of double-sided adhesive sheets] Each characteristic of the double-sided adhesive sheet obtained in each Example and Comparative Example was measured by the following procedures. The obtained results are listed in Table 1 below.

<Water Vapor Transmission Rate> The separator on the light release side of the 50 μm-thick adhesive sheet with release sheet produced in Examples and Comparative Examples was peeled off and attached to the nonwoven fabric using a hand roller. Wipes (manufactured by Nepi wipe and Nepia companies). Then, the separator on the lightly peeled side of the 50 μm-thick adhesive sheet produced in Examples and Comparative Examples was peeled off again, and the double-sided adhesive sheets were bonded to each other in a non-woven sheet with the warp peeled off. The adhesive surface of the separator on the re-peelable side of the lining adhesive sheet was used to prepare a sample piece with the structure of non-woven fabric sheet/adhesive layer (thickness 100 μm)/repeelable separator lined with a non-woven sheet with an adhesive layer thickness of 100 μm. . Then, on a glass bottle with an opening diameter of 2.5 cm in which 50 ml of distilled water was placed, the separator on the heavy peeling side of the sample piece was peeled off so that the adhesive surface came to the side of the bottle, and the sample piece was covered with it. The opening of the bottle and cap it. Furthermore, a sealing tape was used to fix the edge of the sample piece covering the opening of the bottle so as not to stick to the opening and to completely seal the glass bottle with the sample piece. The bottle was placed in an oven set at 40° C. and 20% RH without tilting the bottle (in other words, without causing water to come into contact with the sample) and processed for 24 hours. The weight of the water before and after the treatment was measured to determine the weight of the water loss, and the water vapor transmission rate in g/m ² /24h was determined by calculation.

＜Water Absorption Rate＞ Only the adhesive layers of the double-sided adhesive sheets with a thickness of 50 μm produced in the Examples and Comparative Examples were overlapped, and the adhesive layers with a thickness of about 5 mm were cut into 5 cm × 5 cm squares to prepare samples for water absorption evaluation. . Next, the sample for water absorption evaluation was placed in a glass petri dish that had been weighed in advance. After processing in a drying oven at 105° C. for 5 hours, it was taken out from the drying oven and the petri dish was quickly weighed. The absolute dry weight of the sample for water absorption evaluation was determined by subtracting the weight of the petri dish weighed in advance. Then, place the evaluation sample together with the petri dish in a constant temperature and humidity layer at 85°C and 95%RH for 24 hours, and then take it out (at this time, if there are water droplets attached to the evaluation sample or the petri dish, Wipe it), quickly weigh the petri dish together, and measure the weight of the sample for water absorption evaluation after absorbing water by subtracting the weight of the petri dish in the same manner as when determining the absolute dry weight. The water absorption rate is determined by the following formula 1. (Water absorption rate) = (weight of sample for evaluation of water absorption after water absorption) / (weight of sample for evaluation of absolutely dry water absorption) × 100...Equation 1

＜Sulfur content＞ The 50 μm-thick adhesive sheet with a release sheet produced in the Examples and Comparative Examples was cut into three pieces of 5 cm × 5 cm. Then, peel off the separator on the light-peel side and the separator on the heavy-peel side of each adhesive sheet with a peel sheet, remove only the adhesive layer, measure the weight, put it into a decomposition container, and add 5 ml of nitric acid and 0.2 ml of hydrogen peroxide. , using a microwave decomposition system (MARS5 manufactured by CEM Company) for pressurized acid decomposition. After the decomposition was completed, as measurement data, the decomposition solution of three pieces of each level was mixed and quantified into 20 ml, and an inductively coupled plasma (ICP) optical emission spectrometer (ICP-OES) was used. The sulfur content is quantified using CIROS 120 manufactured by the manufacturer, and is converted into the amount of sulfur (mg) per 1 kg of double-sided adhesive sheet and is used as the sulfur content.

＜380 nm transmittance＞ Cut the 50 μm-thick adhesive sheet with a release sheet produced in the Examples and Comparative Examples into 50 mm × 50 mm, peel off the separator on the light release side, and use a manual roller to laminate it so that air does not enter. on a glass slide (manufactured by Shonami Glass Co., Ltd., S9112). Next, the separator on the heavily peeled side was peeled off to prepare an evaluation sample having a glass/adhesive layer structure. The spectral transmittance of the evaluation sample at a wavelength of 380 nm was measured using a self-recording spectrophotometer (model: UV-3100PC, manufactured by Shimadzu Corporation).

＜Gel fraction＞ The 50 μm adhesive sheet with a release sheet produced in the Examples and Comparative Examples was cut into 10 cm × 10 cm. Next, the separator on the light-peel side and the separator on the heavy-peel side of each adhesive sheet with a peel sheet were peeled off, and only 0.1 g of the adhesive layer (double-sided adhesive sheet) was weighed, collected into a sample bottle, and ethyl acetate 30 was added. ml and warmed to 40°C while shaking for 24 hours. Thereafter, the contents of the sample bottle were separated by filtration using a 150-mesh stainless steel metal mesh, and the residue on the metal mesh was dried at 100° C. for 3 hours to measure the dry mass (g). The gel fraction was calculated from the obtained dry mass by the following formula 2. Gel fraction (mass %) = (dry mass/collected mass of double-sided adhesive sheet) × 100...Equation 2

[Evaluation of double-sided adhesive sheets] Each evaluation of the adhesive sheet with a release sheet obtained in each Example and Comparative Example was performed by the following procedure. Among the obtained results, the results other than the total light transmittance and the haze value are described in Table 1 below.

＜Ion migration suppression＞ (Preparation of conductive film for evaluation) Silver paste (RAFS059 manufactured by TOYO CHEM) was screen printed on a 100 μm thick PET film (Cosmoshine A4360 manufactured by Toyobo Co., Ltd.) that has been easily bonded. ), pattern printing is performed so that the two wirings including the lead wiring portion are linear and parallel as shown in FIG. 3 . Thereafter, heat treatment was performed at 135° C. for 30 minutes to harden the silver paste, thereby obtaining a conductive film for evaluation including silver wiring as shown in FIG. 3 . The width of the two wirings is 40 μm respectively, and the distance between the wirings is 15 μm.

(Preparation of samples for evaluation) The separator on the light release side of the adhesive sheet with a release sheet produced in the Examples and Comparative Examples was peeled off, and the adhesive surface was bonded to a 100 μm PET film (Cosmoshine manufactured by Toyobo Co., Ltd. using a manual roller). )A4360), a laminated film with a structure of PET film/adhesive layer/releasable side separator is obtained. Then, the separator on the heavily peeled side was peeled off from the laminated film, and was bonded to the wiring of the conductive film for evaluation produced as shown in Figure 4. After autoclaving treatment at 30°C and 0.5 MPa for 30 minutes, Leave it at 23°C and 50% relative humidity (RH) for 24 hours to prepare a sample for evaluation.

(Evaluation of ion migration suppression effect) A circuit structure after wiring (parallel wiring) as shown in Figure 5 was formed on the evaluation sample. While applying a direct current (DC) voltage of 15 V, the ion migration test was conducted at 85°C and 95%RH for 240 hours. The wiring space of the bonded portion of the adhesive layer (double-sided adhesive sheet) of the evaluation sample treated as above was observed with an optical microscope, and the ion migration suppression effect was evaluated based on the evaluation criteria shown below. Furthermore, in any of the samples of Examples and Comparative Examples, floating, peeling, bubbles, etc. did not occur. A: No dendrite formation or yellow (or orange) exudation-like discoloration was observed between wirings. B: A slight yellow (or orange) discoloration like bleeding is observed between the wirings. C: The formation of dendrites or yellow (or orange) exudation-like discoloration was observed between wirings.

＜Resistance value increases＞ (Production of conductive film for resistance value evaluation) Silver paste (RAFS059 manufactured by TOYO CHEM) was screen printed on a 100 μm thick PET film (Cosmoshine A4360 manufactured by Toyobo Co., Ltd.) that has been easily bonded. ) to print a mesh pattern having measurement electrode portions (four corners) at both ends as shown in Figure 6 . Thereafter, heat treatment was performed at 135° C. for 30 minutes to harden the silver paste, thereby obtaining a conductive film for resistance value evaluation including silver wiring as shown in FIG. 6 . The pitch of the mesh pattern is 500 μm and the line width is 15 μm.

(Preparation of samples for resistance value evaluation) The separator on the light release side of the adhesive sheet with a release sheet produced in the Examples and Comparative Examples was peeled off, and the adhesive surface was bonded to a 100 μm PET film (Cosmoshine manufactured by Toyobo Co., Ltd. using a manual roller). )A4360), a laminated film with a structure of PET film/adhesive layer/releasable side separator is obtained. Then, the separator on the heavily peeled side was peeled off from the laminated film, and was bonded to the wiring of the conductive film for resistance value evaluation produced as shown in Figure 7, followed by autoclave treatment at 30°C and 0.5 MPa for 30 minutes. , leave it for 24 hours under the conditions of 23°C and 50%RH, and prepare a sample for resistance value evaluation.

(Resistance value increases at 85°C and 95% treatment) The initial resistance value between the measurement electrode portions at both ends of the conductive portion of the resistance value evaluation sample was measured using a tester. Thereafter, after processing at 85° C. and 95% RH for 240 hours, the tester was used again to measure the resistance value between the electrodes. Using the average value of the resistance values before and after the treatment of n=3 measured as above, the resistance value increase rate was determined using the calculation formula of the following Equation 3, and the resistance value increase was evaluated based on the evaluation criteria shown below. Furthermore, in the resistance value evaluation samples of any of the Examples and Comparative Examples, floating, peeling, bubbles, etc. did not occur. (Rise rate of resistance value) = (Resistance value after 85°C, 95% treatment)/(Initial resistance value)...Equation 3 A: The resistance value rising rate is less than 1.0. B: The resistance value increase rate is more than 1.0 and less than 1.05. C: The resistance value increase rate is 1.05 or more.

(Resistance value increases during UV treatment) Instead of treating at 85°C and 95%RH for 100 hours, use a Xenon Super Weather meter (Super Xenon Weather Meter manufactured by Suga Testing Machine Co., Ltd.) Super Xenon Weather meter (SX75) was treated in the same manner as "Resistance value increase at 85°C, 95% treatment" except that it was treated at 70 W/m ² and the black panel temperature was 65°C for 100 hours, using the following equation 4 The resistance value increase rate is calculated using the calculation formula, and the resistance value increase is evaluated based on the evaluation criteria shown below. Furthermore, in the resistance value evaluation samples of any of the Examples and Comparative Examples, floating, peeling, bubbles, etc. did not occur. (Resistance value increase rate) = (Resistance value after UV treatment) / (Initial resistance value)... Equation 4 A: The resistance value increase rate is less than 1.0. B: The resistance value increase rate is more than 1.0 and less than 1.05. C: The resistance value increase rate is 1.05 or more.

＜Chroma b* value＞ In the same manner as the evaluation sample prepared for the measurement of "380 nm transmittance", an evaluation sample having a glass/adhesive layer structure was prepared, and the CIE1976L*a*b* table was measured based on JIS Z8781-4:2013. b* in the color family.

＜Total light transmittance and haze value＞ In the same manner as the evaluation sample prepared for the measurement of "380 nm transmittance", an evaluation sample having a glass/adhesive layer structure was prepared, and the total light transmittance of the obtained sample was measured in accordance with JIS K 7361-1. Rate. In addition, the haze value of the obtained sample was measured based on JIS K 7136. These measurements were performed three times, and the average value was used as each measurement value. An integrating sphere type light transmittance measuring device (NDH-5000, manufactured by Nippon Denshoku Industries Co., Ltd.) was used in the measurement. As a result, the total light transmittance of the double-sided adhesive sheets produced in the Examples and Comparative Examples was 90% to 100% in an environment of 23°C and a relative humidity of 50%. The haze values below are all less than 1%.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example 1 Comparative example 2 Comparative example 3 Adhesive composition (Meth)acrylate having a branched chain having 8 to 18 carbon atoms [mass %] 2EHMA 2EHA 2EHMA 2EHA 2EHMA 2EHMA 2EHMA 2EHMA - 85% 85% 95% 95% 70% 85% 95% 85% - Other (meth)acrylates [mass%] - - - - - - - - BA - - - - - - - - 85% Hydroxyl-containing (meth)acrylate [mass %] 2HEA 2HEMA 2HEA 2HEMA 2HEA 2HEA 2HEA 2HEA 2HEA 15% 15% 5% 5% 30% 15% 5% 15% 15% water vapor transmission rate g/m ² /24hr 156 183 124 132 390 310 154 160 520 water absorption % 0.6 0.6 0.5 0.5 0.9 0.8 0.5 0.6 1.5 Sulfur content mg/kg Below detection limit Below detection limit 34 34 Below detection limit Below detection limit 60 Below detection limit Below detection limit 380 nm transmittance % 19 19 19 19 19 19 19 86 19 gel fraction % 64 62 63 59 63 30 54 55 65 Ion migration inhibition A A A A B B A A C Resistance value rises Moist heat treatment (85℃ 95%) A A B B A A C A A UV irradiation B B B B B B C C B Chroma b* value 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.1 0.3

As can be seen from Table 1, when the optical member constituting a display device equipped with a touch panel includes a metal conductive portion, the double-sided adhesive sheet of the present invention can suppress the formation of the metal conductive portion when the optical members are bonded to each other. ion migration, and can suppress changes in resistance value caused by hot and humid environments and ultraviolet rays. In Comparative Example 1, the sulfur content of the double-sided adhesive sheet exceeded the range specified by the present invention, and the resistance value changed greatly due to a hot and humid environment and ultraviolet rays. In Comparative Example 2, the spectral transmittance of the double-sided adhesive sheet at a wavelength of 380 nm exceeds the range specified by the present invention, and the resistance value changes greatly due to ultraviolet treatment. In Comparative Example 3, the water vapor transmittance and water absorption rate of the double-sided adhesive sheet exceeded the range specified by the present invention, and when the optical components were bonded to each other, ion migration in the conductive portion was significantly caused.

1: Double-sided adhesive sheet with peel-off sheet 11: Double-sided adhesive sheet (adhesive layer) 12a, 12b: Peel-off sheet 20: Laminated body 21: Double-sided adhesive sheet (adhesive layer) 22:The first connected object 24: The second connected body 27a, 27b, 27c, 27d: conductive part

FIG. 1 is a schematic diagram showing an example of a structural cross-section of the double-sided adhesive sheet of the present invention. FIG. 2 is a cross-sectional view showing an example of a structural cross-section of the laminated body of the present invention. FIG. 3 is a schematic diagram showing the structure of a conductive film for evaluation including silver wiring. FIG. 4 is a schematic diagram showing the structure of a sample for evaluation of ion migration suppression. FIG. 5 is a schematic diagram showing a circuit configuration used for evaluation of ion migration suppression. FIG. 6 is a schematic diagram showing the structure of a conductive film for resistance value evaluation including silver wiring. FIG. 7 is a schematic diagram showing the structure of a sample for resistance value evaluation.

1: Double-sided adhesive sheet with peel-off sheet

11: Double-sided adhesive sheet (adhesive layer)

12a, 12b: Peel-off sheet

Claims (9)

A double-sided adhesive sheet for bonding a first adherend and a second adherend, both of which are optical members constituting a display device equipped with a touch panel, and in the double-sided adhesive sheet, the first adherend is At least one of the adherend and the second adherent has a metal conductive part, a sulfur content of 50 mg/kg or less, a spectral transmittance of 30% or less at a wavelength of 380 nm, and a water vapor transmittance of 400 g. /m ² /24h or less, or the water absorption rate is less than 1.0%. The double-sided adhesive sheet according to claim 1, wherein the first adherend is a touch panel, The second adherend is an image display device or a cover material. The double-sided adhesive sheet as described in claim 1, wherein the total light transmittance is 90% to 100%, the haze value is less than 1%, and the chromaticity is specified by the International Commission on Illumination 1976 L*a*b* color system. b* is -1~1. The double-sided adhesive sheet according to claim 1, wherein the double-sided adhesive sheet has an adhesive layer, The gel fraction of the adhesive layer is 40% to 90%. The double-sided adhesive sheet according to claim 1, wherein the double-sided adhesive sheet has an adhesive layer, The adhesive layer includes a base polymer containing 70% to 98% by mass of units derived from (meth)acrylate having a branched chain with carbon numbers of 8 to 18, and a base polymer derived from (meth)acrylate containing a hydroxyl group. ) A base polymer containing 1% to 20% by mass of acrylate units. A laminate including: the double-sided adhesive sheet according to any one of claims 1 to 5; and The first adherend and the second adherend are arranged on both surfaces of the double-sided adhesive sheet and are optical members constituting a display device equipped with a touch panel, and in the laminate, At least one of the first connected body and the second connected body has a metal conductive part. The laminated body according to claim 6, wherein the first adherend is a touch panel, The second adherend is an image display device or a cover material, At least one of the touch panel, the image display device, or the cover material includes a transparent conductive film having a mesh conductive portion and lead wiring connected to the mesh conductive portion. The laminated body according to claim 6, wherein the conductive portion contains silver or copper. A method for manufacturing a laminated body, including the step of bonding the double-sided adhesive sheet according to any one of claims 1 to 5 and a first substrate that is an optical member constituting a display device equipped with a touch panel. The step of pressurizing is carried out in a state where one of the surfaces of the body and the second bonded body are in contact with each other, At least one of the first connected body and the second connected body has a metal conductive part.